(a) Field of the Invention
This invention generally relates to field of devices for unloading trucks, and more particularly, but not by way of limitation, to a portable sliding device for unloading the bed of pickup trucks and the like.
(b) Discussion of the Prior Art
The need to devise a System or apparatus for unloading the bed of a truck has long been recognized. However, attempts at solving the problems associated with unloading the bed of a truck have typically followed similar approaches. Perhaps the most common type of unloading mechanism is the well known hydraulic lifting device that simply tilts the bed of larger trucks. Moreover, the devices employed for unloading smaller trucks or utility vehicles have resulted in complicated solutions that require significant modifications to the vehicle. For example, in U.S. Pat. No. 2,797,828 to Fritsche an apparatus requiring guide rails or stationary supports is taught. The Fritsche device allows the convenient loading and unloading of the back of a vehicle with light loads such as boxes that may be lifted by an individual. The device adds convenience in that it makes it easy to load something on a tailgate, for instance, and then use the device to stow the load into the vehicle's cargo carrying area. The design, although convenient, requires attachment of guides or rails to the vehicle. Moreover, the device is intended to stay inside the vehicle, thereby permanently modifying the vehicle's interior.
In yet another example, U.S. Pat. No. 3,084,816 to Bozio, another rail or guide mounted device is taught. The Bozio device offers very similar advantages as does the Fritsche invention. The Bozio device requires much more modification of the vehicle than does the Fritsche device, but provides a much larger loading zone and allows for the access of hidden panels such as the panels that may be used to conceal a spare tire, for example. The Bozio device suffers from the same limitations as the Fritche design, but suffers from additional limitations in that it longer tracks which may become filled with debris a and jammed.
In yet another example, U.S. Pat. No. 5,454,684 to Berens. The Berens patent teaches the use of a removeable cargo box between a pair of rails or support guides. To unload the vehicle, the removeable cargo box slides out and swings over the ends of the rails to dump the materials out of the cargo box. This approach requires a sub-frame, rails, and a large cargo box. In addition to the mechanical complications of this system, it is apparent that the large box and sub assembly will be cumbersome and difficult to store whenever the device is not in use. Moreover, the installation of the device may always require several individuals in order to install the device in a vehicle. Still further, the device itself takes up a significant amount of room which impairs the amount of cargo that can be carried with the vehicle when the device is in use.
In yet another approach, U.S. Pat. No. 5,184,931 to Safko, the use of a cargo box with a pair of belts are used for pulling the cargo box out of the bed of a truck. The Safko device is a simple, effective approach, but the device suffers from the limitation that it is large and essentially unsupported, and that because of its size it will likely remain in the bed of the truck when not in use. This kind of an arrangement is very dangerous since the large box may be tossed from the bed of the truck in the event of an accident. Moreover, if the box is allowed to remain installed on the truck, the space between the bed and the cargo box is likely to collect water and debris, which can speed up the corrosion of the bed of the truck. Still further, the device does not give the driver of the truck any indication of when the dumping operation is finished. Thus the driver may continue to continue back up over the belting until the belting is torn off of the cargo box or the cargo box is destroyed.
Other examples of devices that carry and unload cargo on the bed of a truck include U.S. Pat. No. 3,381,835 to Lee, which also provides rails and a substructure to hold a cargo box. U.S. Pat. No. 3,687,314 to Haugland, which teaches the use of a sliding platform made from hinged sections that allow for the creation of a loading and unloading ramp for use with snowmobiles and the like. In yet another example U.S. Pat. No. 3,768,673 to Nydam et al. teaches the use of a system with rails which includes an extendable platform that can carry a cargo box. The extendable platform serves as a ramp, bridge, and the like. Still another example is U.S. Pat. No. 2,852,303 which is a rail mounted extension to the cargo box. The examples that use rails suffer from the limitations of complexity, weight, and impractical stowability.
Other devices, such as the Haugland device and the device taught in U.S. Pat. No. 5,090,335 to Russell, teach the use of rollers to impart motion on to a platform or ramp. The Russell device is limited in that it is really not well suited for carrying loads of material or for quick unloading of any materials that may be carried on top of the device. Similarly, the Hughland device provides good carrying capabilities for snowmobiles and the like, but is really not designed to solve the problems encountered when the vehicle is used for hauling lawn clippings, or other refuse.
Thus there remains a need for a simple device for supporting and unloading materials from the bed of a truck in a quick manner. Moreover there remains a need for a simple truck unloading apparatus that is inexpensive, requires little or no modifications to the vehicle, and that can be conveniently carried and stored when not in use.